An example of conventional in-vehicle wireless communication apparatus that reports (a) the stop of power supply from a vehicle battery and (b) the switch of the vehicle battery to a supplemental battery is disclosed in, for example, Japanese patent document 1 JP-A-2003-112606. This apparatus serves as a theft prevention apparatus.
The above theft prevention apparatus monitors, in a theft monitor mode that is set by a monitor setting switch, power voltage of the vehicle battery by a power controller, and switches the vehicle battery to the supplemental battery when the power supply from the vehicle battery stops, with an output of a report signal that reports the switching of the battery. Then, the power controller determines the theft of the vehicle upon detecting the switching to the supplemental battery, while maintaining the operation of the theft prevention apparatus by using the supplemental battery, and performs a theft report process. In this manner, the theft of the vehicle by a thief who disconnects the vehicle battery for preventing the theft report is securely warned and prevented.
Japanese Patent Laid-Open No. 2003-112606 bulletin (Japanese patent document 1)
As observed above, the theft prevention measure is intended and expected to operate as a longer a time as possible. Therefore, one possible solution for the extended operation time is carrying a large capacity battery. However, the large capacity battery occupies a large volume, which leads to an increase of the volume of the wireless communication apparatus. The increase of the apparatus volume makes it difficult for the apparatus to fit in a limited installation space in the vehicle.